《Python3-标准库》讲解

一、string：文本常量和模板
 函数：capwords()
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 import string

 s = 'The quick brown fox jumped over the lazy dog.'
 print(s)
 print(string.capwords(s))

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The quick brown fox jumped over the lazy dog.
The Quick Brown Fox Jumped Over The Lazy Dog.
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这个代码的结果等同于先调用split()，把结果列表中的单词首字母大写，然后调用join()来合并结果.
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字符串模板，将作为内置拼接语法的替代做法.
   代码清单
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import string

values = {'var': 'foo'}

t = string.Template("""

Variable         : $var
Escape           : $$
Variable in text : ${var}iable
""")

print('TEMPLATE:', t.substitute(values))

s = """
Variable         : $(var)s
Escape           : $$
Variable in text : ${var}iable

"""

print('INTERPOLATION:', s % values)

s = """
Variable         : {var}
Escape           : {{}}
Variable in text : ${var}iable

"""

print('FORMAT:', s.format(**values))
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结果
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TEMPLATE:

Variable         : foo
Escape           : $
Variable in text : fooiable

INTERPOLATION:
Variable         : $(var)s
Escape           : $$
Variable in text : ${var}iable

FORMAT:
Variable         : foo
Escape           : {}
Variable in text : $fooiable
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safe_substitute()方法
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代码清单
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import string

values = {'var': 'foo'}

t = string.Template("$var is here but $missing is not provided")

try:
    print('substitute()    :', t.substitute(values))
except KeyError as err:
    print('ERROR:', str(err))
   
print('safe_substitute():', t.safe_substitute(values))
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高级模板
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delimiter和idpattern类属性。
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代码清单
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import string

class MyTemplate(string.Template):
    delimiter = '%'
    idpattern = '[a-z]+_[a-z]+'
   
template_text = '''
    Delimiter : %%
    Replaced  : %with_underscore
    Ignored   : %notunderscored
'''

d = {
    'with_underscore': 'replaced',
    'notunderscored': 'not replaced',
}

t = MyTemplate(template_text)
print('Modified ID pattern:')
print(t.safe_substitute(d))
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